1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly relates to reliability of an aluminum or aluminum alloy interconnect structure.
2. Description of Related Art
Technology of inlaying refractory metal such as, for example, tungsten in order to form contact holes in semiconductor processing of interconnect structures essential to planarization techniques has been adopted in recent years. A film of, for example, titanium nitride is formed as a refractory metal encapsulation layer after forming via holes in an inter-layer insulation film formed on a lower layer interconnect. A thin film of tungsten, which is a refractory metal, is then formed within this via hole. After this, etch-back techniques etc. are employed to ensure that tungsten only remains within the via hole. An aluminum alloy of an upper layer interconnect connected to this tungsten is then formed on the inter-layer insulation film. Electromigration occurring with aluminum alloy and inlaid tungsten is introduced in, for example, the paper xe2x80x9cElectromigration in two-level interconnect structures with Al alloy lines and W studs (1992 American Institute of Physics. VOL. 72.NO. 1, July 1992)xe2x80x9d, etc.
When an aluminum alloy interconnect is connected to a high potential side in a multilayer interconnect structure employing a layer of inlaid tungsten, electrons migrate from the lower interconnect, through the via holes, to the aluminum alloy interconnect. As a result, the origin of the commencement of migration of the aluminum atoms is concentrated around the via holes, and aluminum at an end of the upper layer interconnect on the high potential side is lose so as to create voids.
It is therefore the object of the present invention to provide an interconnect structure capable of suppressing loss of aluminum at an end of a high potential-side interconnect.
In order to achieve the aforementioned object, a semiconductor device of the present invention comprises a first interconnect and a second interconnect formed from aluminum or aluminum alloy at a different layer to the first interconnect and being connected to the first interconnect via metal not including aluminum, with a hole being provided at the second interconnect.